opencpn:manual:plugins:sar:sar_liferaft.jpg
SAR-plugin (SAR = Search And Rescue)
opencpn:manual:plugins:sar:sar_icon.png
This document is about SAR-plugin (SAR-pi). The plugin is developed by SaltyPaws, based on the (external) software “SAR Search patterns” by Andres Ruiz González.
This document is by no means meant to replace official SAR-manuals like the IAMSAR (International Aeronautical and Maritime Search and Rescue) Manual.
The sole purpose of this document is to explain SAR-pi so that you can use that plugin in OpenCPN.
SAR is a plugin that can generate different types of Search and Rescue-patterns directly from within OpenCPN.
You can save these patterns as GPX-files.
These GPX-files can then be loaded in OpenCPN and used as routes to follow in order to perform an efficiënt search and rescue-operation.
Note: In this document “Search And Rescue will be shortened to “SAR”.
When a SAR-operation is necessary, there is absolutely no time to lose.
It can be a fellow sailor who is in distress, or a loved-one who fell overboard during a dark and rough night.
It is very important that your search operation is as efficiënt as possible. Meaning that -with the required speed-, you cover a maximum of the search-area in a minimum of time. In order to achieve that, it is best to follow certain patterns. These search-patterns have proven to give the best results for certain conditions.
When the need arises, you can start thinking about making a search pattern. And then you have to actually lay out that pattern as a track or route to follow. But that will take you some time and it requires clear thinking. And especially in those situations “clear thinking” is challenged by a lot of other worries on your mind.
Let SAR-pi do the work for you!
Note: in most circumstances SAR-operations are coördinated by the Coast Guard or other professional search and rescue-organisations. These operations are coordinated and executed by highly trained specialists and follow specific rules and procedures.
This manual is meant primarily for situations where you are all on your own and you are the first (or only) ship in the vicinity.
There is no time to lose, so choose a search pattern that is best suited for the situation.
In short:
(but keep in mind: this procedure is less suited to be used simultaneously by multiple vessels)
(but keep in mind: this procedure is less suited to be used simultaneously by multiple vessels)
Nobody is eager to get involved in a situation that necessitates a SAR-operation. Not as the object that has to be found and not as a vessel that participates in the SAR-operation. But if you do, you will have to understand that one of the keys to a successful operation is coordination and the avoidance of miscommunication. That involves understanding some specific terms and abbreviations.
When two or more SRU's are working together on the same mission, one person on scene may be needed to coordinate the activities of all participating SRU's.
The person in charge of the first SRU to arrive at the scene will normally assume the OSC function until the SMC arranges for that person to be relieved.
The OSC is normally a person in charge of a:
In restricted visibility, or if sufficient SRU's are not available, it will probably be better to have the first SRU break off the expanding square search and be available for initiation of a parallel track search.
Search patterns are for the “S”-part of SAR. But let's not forget the “R”-part (after all, that “R”-part is the one and only reason for the “S”-part). So prepare yourself to do what has to be done once the search proves succesful. That will probably be:
Be aware of drift!
Precise search pattern navigation using high-precision methods such as GPS-systems will produce good patterns relative to the ocean bottom, but not relative to the drifting search object. This could allow the search object to drift out of the search area. Therefor the currents and other forces affecting the search object's drift during the search should be taken into careful consideration. If a smoke float or other highly visible, expendable object is available, it should be deployed at datum and the pattern should be performed relative to it.
Be aware of the risks involved!
Vessels proceeding to assist should assess the risks they may encounter on scene, including the risks such as those associated with leaking cargo, etc. Information should be sought as necessary from the distressed craft and/or from the RCC or, if no RCC is involved, the OSC.
Now you're ready to read on….
Back to top of page ↑[1832]
Note: In this section the instructions are specifically for SAR-pi, but there is a dedicated page in the manual with information about Downloading, Installing and Enabling Plugins in general. That dedicated page can be found here: Plugins-Install and Enable.[1833]
SAR-pi can be downloaded from http://www.opencpn.org/index.html[1834]
Click “Downloads”
Click “Plugins for OpenCPN 4.2 & 4.4” Look for “SAR””
How to install the plug-in.
Make sure you choose the file that is compatible with your computersystem. In this manual we presume it's Windows, so we choose the Windows setup-package. Download the file (double-click). We assume you know where to find the files you download from the Internet (if you don't: quit now and read the manual of your computer before doing anything else with it ). Double-click the downloaded file and follow the set-up instructions. That's it. But before you can actually use the plug-in, you first have to enable that plug-in in OpenCPN.
Enabling the plug-in in OpenCPN.
Open (or restart) OpenCPN.
Click Tools-Options-Plugins.
Scroll down untill you see the SAR-pi.
Click “Enable” and then “Preferences”.
The list of preferences is simple:
It's best to leave both checkboxes ticked, so that SAR-pi can use your ship's position or your cursor's position as a starting-point for the SAR-patterns.
opencpn:manual:plugins:sar:sar_preferences_02.png
Click “OK” to exit the “Route Preferences” screen and then “OK” to exit the “Options” screen.
Now the SAR-pi icon should appear somewhere in your OpenCPN Toolbar.
opencpn:manual:plugins:sar:sar_icon.png
Back to top of page ↑[1835]
The ability to quickly deploy efficient search and rescue patterns is relevant since no matter how developed our means of transportation may get, the possibility of an emergency arising due to an accident or other reasons can never be ruled out. Specific SAR patterns have been worked out to deal with maritime emergencies. These various search and rescue patterns will be explained below.
Types of Search and Rescue Patterns
SAR-pi can generate 4 different types of SAR-patterns. They are:
In the section “Operation” we will explain the patterns in some more detail.
Back to top of page ↑[1836]
Click the SAR-icon in the Toolbar
opencpn:manual:plugins:sar:sar_icon.png
Choose the desired search pattern. In this example: SAR: Trackline.
The plugin has a window with two sections: the top half and the bottom half.
Here you can set the type of search-pattern. In this screenshot a pattern of the type “Parallel Search” (“Trackline”) is chosen.
opencpn:manual:plugins:sar:sar_parallel_01.png
In each search pattern you can enter several parameters, for instance the search speed. They will be explained in more detail in the specific section for each type of pattern There are also buttons to calculate the distance and time of the search pattern and to generate a GPX-file for that pattern.
But before you generate the GPX-file, go to the bottom half of the window.
opencpn:manual:plugins:sar:sar_results_01.png
The bottom half of the window is for entering the start-position of the search pattern and for showing the results (the distance of the calculated search pattern and the time it will take to complete that pattern). You can also enter a name for the search-pattern (Route).
When the parameters for the search-pattern are entered, you click “Calculate” and find out that (in this example) the pattern will cover 14 NM and will take 2.8 hours to complete.
opencpn:manual:plugins:sar:sar_parallel_results.png
If you want the search pattern to start at your ship's position, you go to the bottom half of the window and click “Ship”.
opencpn:manual:plugins:sar:sar_copy_ship_pos.png
You can also use the position of your cursor on the screen. For instance when you are still some distance away from the area where the search has to take place. A message will pop up to tell you to select either the Lattitude or the Longitude coordinate field and press Ctrl+S.
opencpn:manual:plugins:sar:sar_copy_cursor_pos.png
A third option is to enter latitude and longitude of the starting position by hand.
For example: you hear a MAYDAY of a ship that is sinking in position 53 degrees 30“ North / 004 degrees 30” East.
Fill in 53, 30, 004, 30 and click “Convert to degree”.
opencpn:manual:plugins:sar:sar_convert.png
Now click “Generate GPX”.
opencpn:manual:plugins:sar:sar_generate_gpx.png
We save the file in a map where we can easily find it. For instance in a map “SAR”.
Back to top of page ↑[1837]
Go in the OpenCPN Toolbar to “Route & Mark Manager” and import the GPX-file as a route.
opencpn:manual:plugins:sar:sar_rte_and_mark_manager_01.png
opencpn:manual:plugins:sar:sar_import_gpx.png
The search pattern will show up as a new route. Make sure it is “visible” (the “eye” should be open).
opencpn:manual:plugins:sar:sar_parallel_route.png
The standard actions can be summed up as:
Back to top of page ↑[1838]
Keywords:
Parallel Search:
Risk with restricted visibility
A parallel track search in restricted visibility poses problems because of the following considerations:
Click the SAR-icon in the Toolbar Choose the desired search pattern. In this case: SAR: Trackline.
opencpn:manual:plugins:sar:sar_tab_parallel.png
Now we have to enter the parameters (“TAB” will bring you to the next field). In this example we have set up a Parallel Search pattern for ship number 1 with the parameters as described in the previous screenshot.
That is:
“Approach course”
The Approach course is the direction you want the “legs” to point. Normally this will be the direction of the drift or, if no drift has to be taken into account, true north. In the following example we have entered 030 degrees (roughly Nort-East).
“Leg distance”
This is the length in nautical miles of each leg.
“Leg spacing”
This is the distance in nautical miles between two (parallel) legs.
Note: when the lookout is positioned high above the water, for instance in a crow's nest, the lookout has a better view and can see object further away than when he would be positioned low above the water. In such cases the distance between the legs can be greater than when the lookout is low above the water. See also the explanation of “Sweep Width”.
“Number of legs”
This the number of legs you want to use in the search pattern. The higher the number, the more legs and the longer the search pattern.
“Search speed”
This is the speed of the searching ship. Note: the higher the speed, the greater the distance you can cover in a given time. But high speed might also result in a bigger risk of passing the position of the searched object without noticing that object.
“For ship number”
You can set a search pattern for 1 ship or for two ships. If you choose “1”, the search pattern will be for ship number 1. If you choose “2”, the search pattern will be for ship number 2. It will have the same starting position (Datum) as the search pattern of ship number 1, but the pattern will be positioned on the opposite side.
We use the position of our cursor as the starting point (as described under “Standard Actions”) and we enter a name for the patter. In this example: Parallel-Test.
opencpn:manual:plugins:sar:sar_name.png
Back in the top half of the window we click “Generate GPX” and save the GPX-file (as described under “Standard Actions”).
opencpn:manual:plugins:sar:sar_parallel_save.png
Note: for some reason the system saves the GPX-file with a double gpx-extension.
opencpn:manual:plugins:sar:sar_gpxgpx.png
In OpenCPN we open the GPX-file as a route (as described under “Standard Actions”) and this is the result.
opencpn:manual:plugins:sar:sar_parallel_result_01.png
The pattern has 4 legs, 0.5 nm apart from each other and the first leg is orientated in the direction 030.
Activate the route and start your SAR-operation!
Note: in these screenshots the “own ship”-icon is pointing upwards (away from the starting-point). In real live it would mean you would have to turn over port to proceed to go “back” to the starting point.
opencpn:manual:plugins:sar:sar_parallel_result_route_act.png
Back to top of page ↑[1839]
If there are two ships participating in the search, you can repeat the proces for “ship number 2”. That second pattern can use other parameters than the pattern for ship number 1. In the following example we assume the “mothership” launches her (faster) RIB.
opencpn:manual:plugins:sar:sar_parallel_ship_02.png
Let us assume that ship number 2 is a RIB that can easily cruise at 15 knots. We set that as the Search Speed. And as that ship is faster, she can cover a larger area in the same amount of time. So we can afford to set the Leg Spacing to a shorter distance. Say 0.25 NM. And we can double the Number of Legs to 8.
Repeat the process of creating the GPX-file, saving it and opening it as a route in OpenCPN.
This is the result with both of the GPX-files loaded. The search-pattern for ship number 2 is on the opposite side of the starting-position.
opencpn:manual:plugins:sar:sar_parallel_result_02ships.png
Note: Suppose there are two ships. One is the relatively big and slow but comfortable mother-ship with her well-equipped navigational area (and of course OpenCPN plus SAR-plugin). The other ship is the small and fast but very uncomfortable RIB that's speeding towards the search-area. Now it is possible to generate the SAR-patterns in the relative comfort of the mother-ship (or even from a shore-based station) and then send the generated GPX-file(s) via email to one or more other ships. Like that RIB. There that GPX-file can be received (and used!) on a mobile phone that has OpenCPN for Android!
Back to top of page ↑[1840]
Keywords:
Starting at the probable location of the target, the search vessels expand outward in concentric squares.
This pattern is the most effective pattern when the location of the search object is known within relatively close limits.
The commence search point is always the datum position.
Expanding square search is often appropriate for vessels or small boats to use when searching for persons in the water or other search objects with little or no leeway.
Due to the small area involved, this procedure is less suited to be used simultaneously by multiplevessels. Accurate navigation is required; the first leg is usually oriented directly into the wind to minimize navigational errors.
Click the SAR-icon in the Toolbar Choose the desired search pattern. In this case: SAR: Expanding Square.
The parameter-window shows these fields:
opencpn:manual:plugins:sar:sar_tab_expanding.png
The approach-course should be set in the direction of the drift, or else to 000 (true North). The rest should be easy to understand, so we will not explain this further. Example: (insert screenshot sar_exp_sq_02a.png)
Following the steps described in “Standard Actions” will give a result that looks like this: (insert screenshot sar_exp_sq_02b.png)
opencpn:manual:plugins:sar:sar_exp_sq_02.png
Back to top of page ↑[1841]
Keywords:
The sector search is employed when the position of the lost ship or lost body is known accurately and the search has to be carried over a small area, say with each leg a length of no more than 2 to 5 NM. It is normally carried out in the area where the casualty or the object has been sighted.
The search pattern will always start from the datum point. This pattern gives a very high probability of detection close to the datum point and spreads the search over the probable area quickly. With a man overboard, the ship returns immediately to the datum or, if the search target is once sighted and then lost, the ship heads for the datum.
All turns are 120 degrees to starboard. Upon completion of the search pattern, re-orient the pattern 30 degrees to the right and research a new pattern (see the dashed lines). This procedure can be repeated three or four times until either the victim is found or the search has been called off.
The advantage of this pattern is that the search vessels cross the datum a number of times. The first step is to determine the drift and carry out the operations in that direction (first leg in the direction of the drift).
A suitable marker (for example, a smoke float or a radio beacon) may be dropped at the datum position and used as a reference or navigational aid marking the centre of the pattern.
An aircraft and a vessel may be used together to perform independent sector searches of the same area.
NOTE: Due to the small area involved and the fact that the search vessels cross the datum a number of times, this procedure is less suited to be used simultaneously by (a lot of) multiple vessels.
Click the SAR-icon in the Toolbar
Choose the desired search pattern. In this case: SAR: Sector Search
The parameter-window shows these fields:
opencpn:manual:plugins:sar:sar_tab_sector.png
The approach-course should be set in the direction of the drift, or else to 000 (true North).
The rest should be easy to understand, so we will not explain this further.
Example:
opencpn:manual:plugins:sar:sar_sector_02.png
Following the steps described in “Standard Actions” will give a result that looks like this:
opencpn:manual:plugins:sar:sar_sector_1cycle.png
Note: the search-patterns are loaded as “routes”. And as with any route, you can adapt the appearance of that route (colour, style and width).
In this case we have chosen “Magenta” as colour and “short dash” as style.
Repeat the process for a second cycle and the result will be this:
opencpn:manual:plugins:sar:sar_sector_2cycles.png
Back to top of page ↑[1842]
Keywords:
In the so-called “oil rig pattern”, the search sectors are placed into four quadrants.
This pattern is meant to be used when someone has fallen from a stationary object (like an oil rig is, or at least is supposed to be) and the search-area is confined to one quadrant.
Click the SAR-icon in the Toolbar
Choose the desired search pattern. In this case: SAR: Oil Rig
The parameter-window shows these fields:
opencpn:manual:plugins:sar:sar_tab_oilrig.png
Example:
opencpn:manual:plugins:sar:sar_oilrig_parameters.png
Note: the field “Number of Legs” is followed by “Degrees”. That word should not be there. Forget it.
Following the steps described in “Standard Actions” (and with these parameters) will give a result that looks like this:
opencpn:manual:plugins:sar:sar_oilrig_result.png
Back to top of page ↑[1843]
This table gives you an estimate of survival times in various water temperatures. This table is only a guideline to emphasize the need for fast action and not a means of setting an arbitrary limit on the search effort.
opencpn:manual:plugins:sar:sar_survivaltimes.png
End of the SAR-pi manual.
Back to top of page ↑[1844]
